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LC-121 Element names should be xml:ids in schemas

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 06 Oct 2000 22:51:26 +0100
To: Tim Berners-Lee <timbl@w3.org>
Cc: www-xml-schema-comments@w3.org
Message-ID: <f5bzokhaba9.fsf@cogsci.ed.ac.uk>
The W3C XML Schema Working Group has spent the last several months
working through the comments received from the public on the last-call
draft of the XML Schema specification.  We thank you for the comments
you made on our specification during our last-call comment period, and
want to make sure you know that all comments received during the
last-call comment period have been recorded in our last-call issues
list [1].

In a message to the XML Schema comments list on 11 May [2] you
requested the WG to make names of elements, types etc. be IDs, and be
called 'id'.  The WG considered this issue at some length in both
face-to-face meetings and email and teleconference discussions, and
have taken your advice, partly:

  1)  All element types defined by XML Schema admit 'id' as an
      attribute with type ID;

  2)  All declarations of element types, simple types and facets
      intended for public use in the XML Schema for schema documents
      have such an 'id' attribute, giving their name;

  3)  However, the 'id' attribute is not required, and is not the name
      of the item.

For example:

      <element name="attribute" substitutionGroup="schemaTop"
               type="topLevelAttribute" id="attribute">
        <annotation>
         <documentation
           source="http://www.w3.org/TR/xmlschema-1/#element-attribute"/>
        </annotation>
      </element>

      <simpleType name="recurringDay" id="recurringDay">
         <restriction base="recurringDuration">
           <duration value="P24H" fixed="true"/>
           <period value="P1M" fixed="true"/>
         </restriction>
      </simpleType>

enabling references of the form

      http://www.w3.org/2000/10/XMLSchema#attribute
      http://www.w3.org/2000/10/XMLSchema#recurringDay

Rationale:

We declined to adopt the final part of your request, per (3) above,
because the impact on usability in the context of a design with six
nameable but clearly distinct kinds of components (type definitions,
element declarations, attribute declarations, attribute group
definitions, model group definitions, notation declarations) of
forbidding name collisions between these different kinds of things
would be too great.  In particular, it would have directly
contradicted the requirement that we reconstruct the facilities of
DTDs insofar as possible.

We recognise that this resolution although it addresses most of your
concern in practice as far as the XML Schema for schemas goes, is not
in principle complete, and are committed to a long-term solution which 
does make all schema components of any schema however defined _ipso facto_
addressable.

It would be helpful to us to know whether you are satisfied with the
decision taken by the WG on this issue, or wish your dissent from the
WG's decision to be recorded for consideration by the Director of
the W3C.

ht

[1] http://www.w3.org/2000/05/12-xmlschema-lcissues
[2] http://lists.w3.org/Archives/Public/www-xml-schema-comments/2000AprJun/0167.html
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2001, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/
Received on Friday, 6 October 2000 17:51:30 GMT

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